Dual acting probe with extractor/guide

ABSTRACT

An electrical probe is designed to test printed circuit boards having contact elements and connectors mounted thereon. The probe has an insulating body carrying two parallel contact blades. A member of insulating material is slideably mounted on the blades and is connected to a plunger assembly. The plunger assembly is used to move the member between two positions. In one position, the ends of the blades are exposed for insertion into a connector for engagement with the contact elements therein. Upon movement of the member from this position, the member engages the connector assembly and facilitates extracting the blades from the assembly. In the other position, the member covers the ends of the blades and is shaped to guide the blades into engagement with the contact elements on the board.

United States Patent Adams et al. [4 1 Sept. 19, 1972v [54] DUAL ACTING PROBE WITH 1,650,779 11/1927 Williams ..324/72.5

EXTRACTOR/GUIDE 2,769,155 10/1956 Wimble ..339/32 R [72] Inventors: Joseph E. Adams, Millbrook; Ed-

Assignee:

mund J. Di Stefano; Arthur E. Enderley, both of Poughkeepsie, all of NY.

International Business Machines Corporation, Armonk, N.Y.

Filed: Dec. 17, 1970 Appl. No.: 99,204

US. Cl. ..324/l58 P, 324/725, 339/45 M Int. Cl. ..G01r l/06, H01r13/62 Field of Search...324/l58 P, 158 F, 158 R, 72.5, 324/149; 339/45 R, 45 T, 45 M, 108 TP, 65,

. 66 R, 66 M, 66 T References Cited UNITED STATES PATENTS Primary Examiner-Rudolph V. Rolinec Assistant Examiner-Ernest F. Karlsen Attorney-Hanifin & Jancin and D. R. McKechnie 5 7] ABSTRACT An electrical probe is designed to test printed circuit boards having contact elements and connectors mounted thereon. The probe has an insulating body carrying two parallel contact blades. A member of insulating material is slideably mounted on the blades and is connected to a plunger assembly. The plunger assembly is used to move the member between two positions. In one position, the ends of the blades are exposed for insertion into a connector for engagement with the contact elements therein. Upon movement of the member from this position, the member engages the connector assembly and facilitates extracting the blades from the assembly. In the other position, the member covers the ends of the blades and is shaped to guide the blades into engagement with the contact elements on the board.

3 Claims, 6 Drawing figures PATENTEDSEP 19 I972 I INVENTORS JOSEPH E. ADAMS EDMUND J, 'D'STEFANO ARTHUR E ENDERLEY 05W W MQ ATTORNEY 1 DUAL ACTING PROBE WITH EXTRACTOR/GUIDE SUMMARY OF THE INVENTION This invention relates to electrical probes for use in measuring and testing electronic devices having printed circuit boards provided with a multiplicity of contact elements and connectors. More specifically, it relates to probes provided with means for facilitating the engagement with and disengagement from the conductive elements to which it will be connected for probing purposes.

The present invention was specifically designed for use in probing an electronic device having a printed circuit board provided with a plurality of parallel ground rails and a multiplicity of square upstanding contact V pins arranged in rows extending parallel to the rails. Various types of connectors and cable assemblies are used to interconnect the terminal pins and rails. One type of connector has a housing enclosing a pair of tun ing fork contact elements, one of which is engagable with the ground rail and the other which is engagable with an adjacent pin. The upper ends of the contact elements are interconnected by a resistor to form what is known as a terminator. The terminator can be connected to an additional cable or not. A second type of connector, known as a single cable connector, includes the same type of contact elements and housing but the upper ends of the contact elements are connected to a cable whose other end may be connected to a similar connector located elsewhere on the printed circuit board. A third type of connector is known as a double. Again, it involves the same housing. However, instead of merely housing a single pair of contact elements connected to one end of a cable, it has two pairs of such contact elements connected to two pairs of cables.

In the testing and probing of such an arrangement, it is necessary at times not only to make a probing engagement with any one of the three different types of connectors described above, but is also necessary at times to be able to directly probe the ground rail and adjacent pin when there is no connector mounted on it. In view of these specific probing requirements of such an arrangement then, it is the principal object of this invention to provide a single probe that is versatile and can be used to probe several different types of contact elements for the purpose of allowing the device associated therewith to be measured or tested.

Other objects of the invention are to provide a probe which aids in making electrical contact with the elements being probed, which can be readily connected to and disconnected from the elements being probed, and which is cheap and easy to use.

Briefly stated, the manner in which these and other objects are obtained is to provide a probe having an insulating body. Two parallel contact arms or blades are mounted on the body. A sliding guide/extractor element of insulating material is mounted on the blades and is moveable therealong, by means of a plunger. The guide is moveable between two extreme positions. In one position, the guide covers the ends of the contact arms and serves to guide the arms onto a ground rail and associated pin by simply pushing the probe thereon. In the other extreme position, the element exposes the ends of the blades so that the ends can be inserted into a connector for engagement with contact elements therein. When it is desired to remove the probe, the plunger is pushed causing the extractor element to hold the connector while the blades are withdrawn therefrom.

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention, as illustrated in the accompanying drawings.

FIG. 1 is a front elevational view of aprobe embodying the invention.

FIG. 2 is a side elevational view, with looking along lines 2-2 of FIG. 1.

FIG. 3 is an enlarged side elevational view of a part of the probe shown in FIG. 1.

FIG. 4 is a bottom view of the element of the probe looking along lines 4--4 of FIG. 3.

FIG. 5 is an enlarged elevational view partly in section illustrating how the probe blades co-act with one type of an electrical device being probed.

FIG. 6 is an enlarged elevational view illustrating how the probe blades co-act with another type of electrical element being probed.

DETAILED DESCRIPTION OF THE INVENTION Referring now to the drawings and more specifically to FIGS. 1 and 2, a probe 10 has an elongated, manually grippable insulating body 11. The upper ends of a pair of parallel conductive contact blades or arms 12 and 13 are embedded in the lower end of body 11. A plunger 14 is located above the upper end of body 11 and is connected to a pair of rods 15. These rods pass through grooves that lie flush with the faces of body 1 l. Rods 15 are connected at their lower ends to an insulating element 16. Two bands 17 and 18 circle the ends of body 11 and hold the rods 15 within the slots for sliding movement therein. Plunger l4 and element 16 are moveable between the two extreme positions shown in FIG. 1 in full and dotted lines, respectively.

The upper ends of arms 12 and 13 are soldered or otherwise connected to a pair of insulated wires 21 whose other ends are connected to a standard connector 22. This allows probe 10 to be connected to the instruments used to test or measure the device being probed.

The upper end of body 11 is notched at 23 so that probe 10 can be manually grasped, in a manner similar to that of a hyperdermic needle, by engaging body 11 between the index and middle fingers in the notched areas while allowing the thumb to rest on plunger 14. This facilitates the extracting movement described below. The length of body 11 is preferably sufficient to allow the upper end of probe 10 to project above any maize of wires and cables that might exist in the device being probed.

As best seen in FIGS. 3 and 4, element 16 is generally in the form of a rectangular block having two slots 25 and 26 extending therethrough for receiving contact arms 13 and 12, respectively. Slots 25 and 26 are dimensioned to allow element 16 to freely slide along arms 12 and 13. The lower faces of element 16 are bevelled or tapered at 28, almost all the way across element 16 so as to leave at one edge thereof a flange 29. The lower edge of element 16 has a flat face 30 which in conjunction with flange 29 provides a T-shaped parts removed,

lower face or end. An upwardly extending groove 32 is cut into the lower end of element 16 for the purpose of guiding contact arm 12 onto a ground rail in a manner more fully pointed out below. A chamfer 33 surrounds the lower middle end of groove 26 and opens through face 30 for the purpose of guiding contact arm 13 onto a contact pin in a manner more fully described below.

Referring now to FIG. 3, the lower ends of arms 12 and 13 are bifurcated to provide tines 34-37. Tines 34 and 35 are bent inwardly slightly towards each other as are tines 36 and 37, the purpose of this shape being to develop a high contact pressure when arms 12 and 13 are engaged with the element being probed. Tine 34 is shorter than the remaining tines so that as the probe is engaged with a ground rail and contact pin, the points in time at which the maximum forces are applied for separating tines 36 and 37 and 34 and 35 do not coincide. This minimizes the maximum force necessary to engage the probe. The arms 12 and 13 are long enough so that when element 16 is in the upper position, the free ends of arms 12 and 13 can be inserted into a connector, such as illustrated with reference to FIG. 6, without being interferred with by element 16.

As indicated previously, the probe was designed for 'use with a specific type of printed circuit board and connector. Examples of the circuit boards and connector assemblies are shown in applications Ser. No. 47,073, filed June 17, 1970 by E. .l. DiStefano et al. for Connector Assembly With Tine Skewing Housing, and application Ser. No. 858,476, filed Sept. 16, 1969, by E. J. DiStefano et al. for Electrical Connector. Both applications are assigned to the assignee of the present application. Reference may be had thereto for a more detailed description of the environment for which the present invention was designed. While it is to be understood that the printed circuit board assemblies for which the invention was designed may have several ground rails and a multiplicity of rows of pins and con nectors mounted thereon, for the purpose of illustrating the invention, the printed circuit board assembly is shown simply as having a single ground rail 41 of upstanding U-shaped cross section and a single contact pin 42 both of which are mounted on a printed circuit board 40. The pin projects upwardly and extends parallel to the adjacent flange of the ground rail 41. The spacing between the center lines of contact arms 12 and 13 is the same as the spacing between pin 42 and such adjacent flange of ground rail 41.

In the operation of probe 10, when it is desired to probe a ground rail 41 and contact pin 42, in a situation where there is no connector mounted thereon, the operation proceeds as follows. First, plunger 14 is depressed until it abuts the upper end of body 1 1. This action moves element 16 to its lowest position. In such a position, the lower edge of element 16 projects downwardly beyond the lower edges of contact arms 12 and 13 so as to bring into play the guiding action of chamfer 33 and slot 32. With element 16 in this lower position, the probe is then manually grasped while maintaining the plunger in its lowest position and brought into alignment above the pin and ground rail. The probe is then pushed downwardly until it is fully seated. As element 16 initially contacts pin 42, chamfer 33 receives the upper end of pin 42 and guides it between tines 36 and 37. This motion spreads tines 36 and 37 apart to develop a high electrical contact pressure. As further downward movement proceeds, tine 34 makes an initial compact with ground rail 31 and it is spread apart to develop the desired high electrical contact pressure between tines 34 and 35 and element 41. With the probe in this position, the various electrical tests and measurements may be taken. To remove probe 10, it is simply pulled upwardly.

FIG. 6 is used to illustrate how probe 10 co-acts with another structure which is to be probed. A connector assembly 44, of a type similar to that disclosed in the aforementioned applications, includes an insulating housing 45. A contact assembly 46 includes two tuning fork connectors (not shown) engaged respectively with contact pin 42 and ground rail 41. The upper end of contact assembly 46 is connected to a tri-wire flat cable 47. The housing 45 has sufficient room therein to allow the insertion of arms 12 and 13 in such a manner that these arms engage the contact elements of contact assembly 46 and also contact pin 42 and rail 41. The operation of probing this device follows. First, plunger 14 is raised to its uppermost position which position is defined by the upper edge of element 16 engaging the lower end of body 11. This exposes the lower free ends of contact arms 12 and 13. Next, the probe 10 is aligned over connector assembly 44 so that contact arm 13 will be aligned over pin 42. Then, body 11 of probe 10 is pushed downwardly causing the contact arms 12 and 13 to enter assembly 44 and make electrical contact with both pin 42, rail 41 and the contact elements of contact assembly 46. To remove probe 10 from this position, body 11 is grasped between the fingers and plunger 14 is pushed downwardly to eventually extract arms 12 and 13 from assembly 44. As element 16 moves downwardly, the bevelled surface 28, brushes or cams past the upper edge of contact as sembly 46 and cable 47 so as to bring the lower edge of flange 29 into engagement with the upper underlying edge of housing 45. At this point, the downward movement of element 16 stops but the continued exertion of force between the fingers now causes body 11 to move upwardly to thereby extract arms 12 and 13. Thus, the extraction is accomplished without exerting any upward force on connector assembly 44 which would tend to disconnect it from contact pin 42 and rail 41.

While the probe 10 has been illustrated for use with only one type of connector assembly 44, which is known as a single because of the fact that it has only a single cable 47 and single contact assembly 46 associated therewith, the probe is also useful for probing connector assemblies known as doubles and terminators. In a double, there are two cables 47 and associated contact assemblies 46 housed in a single housing 45. In this case, there is insufficient room in the housing 45 for the probe to make contact with pin 42 and rail 41. But the probe is used by weding arms 12 and 13 between the upper edges of the contact elements between the adjacent contact assemblies 46. For a terminator, which has a resistor across the upper ends of the contact elements of assembly 46, the arms 12 and 13 are wedged between the resistor and the contact elements. Element 16 is used in the manner previously described to extract arms 12 and 13 from the wedging positions in both double and terminator connectors.

While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of 5 the invention.

What is claimed is:

1. For use in testing a circuit board assembly having a conductive rail and at least one upstanding contact pin spaced from said rail, a probe comprising:

body of insulating material;

a pair of parallel conductive contact blades fixedly mounted on said body and extending beyond one end and being adapted to be conductively engaged with said pin and said rail;

an insulating member surrounding and slideably mounted on the extending portion of said contact blades for movement between a first position exposing the end portions of said blades whereby said blades are adapted to be inserted into said circuit board assembly and a second position covering the ends of said blades, said member being shaped so as to guide said contact blades into contact with said pin and said rail when said member is in said second position;

and means for moving said member between said positions whereby said member is adapted to engage said circuit board assembly for extracting said contact blades therefrom; and means for connecting said blades to a testing circuit connector.

2. A probe in accordance with claim 1, wherein said moving means comprises:

a plunger connected to said body and to said insulating member, said body and plunger being so sized and shaped as to be manually grasped between the fingers for effecting relative movement between said insulating member and plunger and said body.

3. A probe in accordance with claim 1, wherein:

said member is shaped so as to project beyond the ends of said contact blades and is adapted to engage said pin and said rail for guiding said blades into engagement therewith. 

1. For use in testing a circuit board assembly having a conductive rail and at least one upstanding contact pin spaced from said rail, a probe comprising: body of insulating material; a pair of parallel conductive contact blades fixedly mounted on said body and extending beyond one end and being adapted to be conductively engaged with said pin and said rail; an insulating member surrounding and slideably mounted on the extending portion of said contact blades for movement between a first position exposing the end portions of said blades whereby said blades are adapted to be inserted into said circuit board assembly and a second position covering the ends of said blades, said member being shaped so as to guide said contact blades into contact with said pin and said rail when said member is in said second position; and means for moving said member between said positions whereby said member is adapted to engage said circuit board assembly for extracting said contact blades therefrom; and means for connecting said blades to a testing circuit connector.
 2. A probe in accordance with claim 1, wherein said moving means comprises: a plunger connected to said body and to said insulating member, said body and plunger being so sized and shaped as to be manually grasped between the fingers for effecting relative movement between said insulating member and plunger and said body.
 3. A probe in accordance with claim 1, wherein: said member is shaped so as to project beyond the ends of said contact blades and is adapted to engage said pin and said rail for guiding said blades into engagement therewith. 